143 lines
4.5 KiB
C++
143 lines
4.5 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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// Original author: ekr@rtfm.com
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#ifndef transportflow_h__
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#define transportflow_h__
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#include <deque>
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#include <queue>
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#include <string>
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#include "nscore.h"
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#include "nsISupportsImpl.h"
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#include "mozilla/UniquePtr.h"
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#include "transportlayer.h"
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#include "m_cpp_utils.h"
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#include "nsAutoPtr.h"
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// A stack of transport layers acts as a flow.
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// Generally, one reads and writes to the top layer.
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// This code has a confusing hybrid threading model which
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// probably needs some eventual refactoring.
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// TODO(ekr@rtfm.com): Bug 844891
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//
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// TransportFlows are not inherently bound to a thread *but*
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// TransportLayers can be. If any layer in a flow is bound
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// to a given thread, then all layers in the flow MUST be
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// bound to that thread and you can only manipulate the
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// flow (push layers, write, etc.) on that thread.
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//
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// The sole official exception to this is that you are
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// allowed to *destroy* a flow off the bound thread provided
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// that there are no listeners on its signals. This exception
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// is designed to allow idioms where you create the flow
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// and then something goes wrong and you destroy it and
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// you don't want to bother with a thread dispatch.
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//
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// Eventually we hope to relax the "no listeners"
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// restriction by thread-locking the signals, but previous
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// attempts have caused deadlocks.
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//
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// Most of these invariants are enforced by hard asserts
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// (i.e., those which fire even in production builds).
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namespace mozilla {
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class TransportFlow final : public nsISupports,
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public sigslot::has_slots<> {
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public:
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TransportFlow()
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: id_("(anonymous)"),
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state_(TransportLayer::TS_NONE),
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layers_(new std::deque<TransportLayer *>) {}
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explicit TransportFlow(const std::string id)
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: id_(id),
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state_(TransportLayer::TS_NONE),
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layers_(new std::deque<TransportLayer *>) {}
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const std::string& id() const { return id_; }
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// Layer management. Note PushLayer() is not thread protected, so
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// either:
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// (a) Do it in the thread handling the I/O
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// (b) Do it before you activate the I/O system
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//
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// The flow takes ownership of the layers after a successful
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// push.
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nsresult PushLayer(TransportLayer *layer);
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// Convenience function to push multiple layers on. Layers
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// are pushed on in the order that they are in the queue.
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// Any failures cause the flow to become inoperable and
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// destroys all the layers including those already pushed.
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// TODO(ekr@rtfm.com): Change layers to be ref-counted.
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nsresult PushLayers(nsAutoPtr<std::queue<TransportLayer *> > layers);
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TransportLayer *top() const;
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TransportLayer *GetLayer(const std::string& id) const;
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// Wrappers for whatever TLayer happens to be the top layer
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// at the time. This way you don't need to do top()->Foo().
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TransportLayer::State state(); // Current state
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TransportResult SendPacket(const unsigned char *data, size_t len);
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// State has changed. Reflects the top flow.
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sigslot::signal2<TransportFlow *, TransportLayer::State>
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SignalStateChange;
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// Data received on the flow
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sigslot::signal3<TransportFlow*, const unsigned char *, size_t>
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SignalPacketReceived;
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bool Contains(TransportLayer *layer) const;
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NS_DECL_THREADSAFE_ISUPPORTS
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private:
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~TransportFlow();
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DISALLOW_COPY_ASSIGN(TransportFlow);
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// Check if we are on the right thread
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void CheckThread() const {
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if (!CheckThreadInt())
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MOZ_CRASH();
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}
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bool CheckThreadInt() const {
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bool on;
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if (!target_) // OK if no thread set.
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return true;
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if (NS_FAILED(target_->IsOnCurrentThread(&on)))
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return false;
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return on;
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}
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void EnsureSameThread(TransportLayer *layer);
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void StateChange(TransportLayer *layer, TransportLayer::State state);
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void StateChangeInt(TransportLayer::State state);
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void PacketReceived(TransportLayer* layer, const unsigned char *data,
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size_t len);
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static void DestroyFinal(nsAutoPtr<std::deque<TransportLayer *> > layers);
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// Overload needed because we use deque internally and queue externally.
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static void ClearLayers(std::deque<TransportLayer *>* layers);
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static void ClearLayers(std::queue<TransportLayer *>* layers);
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std::string id_;
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TransportLayer::State state_;
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UniquePtr<std::deque<TransportLayer *>> layers_;
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nsCOMPtr<nsIEventTarget> target_;
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};
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} // close namespace
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#endif
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